Hey all,

Wondering if anyone's experienced this.

I just completed a 1500 mile trip in my 06' 2.4 5 speed. One way averaged 34 mpg at 65 the whole way, but on the way back it dropped to 25.2 and stuck that way for the last 280 miles. Still doing 65, same route.

Anyone know why this might be?

 

Uphill vs down hill?
did you buy gas without ethanol when you were out of town?
bring extra weight back with you?

 

Forgot 5th gear? Don't laugh, it's happened.

Difference in gas formulation seems to make sense.

 

against wind on return?

 

Har har on the 5th gear, lol. No.

The elevation didn't vary much in either direction, (yes I am one of those geeks that uses an altimeter app)

Gas formulation wise, I always 91, or 93 octane, whichever is available. I'm thinking it MIGHT be possible that the gas in the destination state could have been a bad batch, that would be my only thought.

Weightwise, nothing was added to the car for the return trip.

In hindsight, I don't think this car has ever been on a LONG trip with little to no variance in RPMs for 500+ miles at a time. I'm wondering if a Seafoam session and oil change may have an effect.

As an extra note, filled up this morning, did the math, and the mileage was accurate, I reset the MPG meter this morning (65mph) on my way to work (32 mile trip) and it dropped back to 25.2.

 

run the full tank and see what the figures change to.

 

I plan to. We'll see what happens....

 

that is 30 percent holy crap

 

Formulation does not mean Octane, it means alcohol and other chemical content.

Why over do the Octane? I thought only the SS needed 91. If the car is tuned from the factory for 87 Octane you are wasting your money. It's yours to use.

 

I've seen this where a bad tank of crap gas will burn thru quickly.. run it down..fill it up with good stuff from a familiar gas stop and see what happens...May also want to pull the ECM fuse and do a reset.